Apple's iPad finally goes on sale outside the United States this week after heavy US demand for the multi-media gadget forced a one-month delay of its international release.

Apple's iPad finally goes on sale outside the United States this week after heavy US demand for the multi-media gadget forced a one-month delay of its international release.

The touchscreen tablet device from the maker of the Macintosh computer, the iPod and the iPhone will be available on Friday in stores in Australia, Britain, Canada, France, Germany, Italy, Japan, Spain and Switzerland.

The Cupertino, California-based Apple plans to bring the iPad to Austria, Belgium, Hong Kong, Ireland, Luxembourg, Mexico, the Netherlands, New Zealand and Singapore in July.

The company co-founded by Steve Jobs had planned to begin selling the iPad internationally in late April but was forced to delay the global debut of the device because of what it said was "surprisingly strong US demand."

Apple said earlier this month that it sold one million iPads in the first 28 days it was available in the United States, less than half the time it took for the company to sell the same number of iPhones.

More than 5,000 applications have been developed for the iPad, according to an Apple spokesman, in addition to the 200,000 programmes already available for the iPhone or the iPod Touch, most of which run on the iPad.

A Wi-Fi version of the iPad, which allows users to watch video, listen to music, play games, surf the Web or read electronic books, went on sale in the United States on April 3 for $499.

A more expensive model featuring both Wi-Fi and 3G cellular connectivity appeared on US store shelves on April 30 for $829.

Capital Markets analyst Mike Abramsky estimated that Apple is selling over 200,000 iPads a week -- more than its estimated Macintosh sales of 110,000 a week and its estimated iPhone 3GS sales of 246,000 a week.

Apple has declined to reveal the number of pre-orders received for the iPad internationally but Abramsky put it at around 600,000.

The US sales figures indicate the iPad is a hit but success did not appear guaranteed when Apple's Jobs unveiled the device at a high-profile media event in San Francisco in January.

"There were plenty of questions before the iPad launch and quite a mixed reaction to it when it was released," said Gartner analyst Charles Smulders.

Critics mocked the name for its resemblance to that of a feminine hygiene product, derided it as a "big iPhone" without a phone or a camera and bemoaned its inability to play Adobe's popular Flash video software.

But the iPad appears to have won over the public with a hip advertising campaign and curious consumers can be seen lining up daily to play with tethered models of the device on display at Apple stores around the country.

"Aside from the design, a key to its success has been getting the product into the hands of consumers," Smulders said. "With a new category of product like this it is difficult to understand its value unless you try it."

"Apple has done a great job seeding the market."

Ben Reitzes of Barclays Capital said he sees potential for the iPad beyond the consumer market.

"Even corporations are piloting the device at a pace that surprises us," Reitzes said. "At the very least we believe the device can tap into the corporate market as a 'log in' device that accesses the network.

"Many of our clients are increasingly using, or intend to use, the device as a reader for research as well," he said.

With success comes competition and imitation.

US computer giant Dell plans to begin selling its own tablet computer, the "Streak," which has a 12.5-centimetre screen compared with the iPad's 24.6 centimetres, in Britain in June and in the United States later in the summer.

And another US computer giant, Hewlett-Packard, recently announced plans to acquire struggling US mobile phone maker Palm and is expected to use its WebOS operating system to develop a tablet computer of its own.